In-line venturi

ABSTRACT

An apparatus for inserting a venturi tube having an inlet, an aspirator inlet and an outlet directly within a fluid flow stream, with the aspirator inlet not in contact with the fluid flow stream is disclosed. A plate having a first aperture leading to the venturi inlet, and a series of second apertures both supports the venturi within a conduit and divides the fluid flow stream into a first stream which flows through the venturi tube and a second stream which flows around the venturi tube. A variety of adjusting mechanisms are disclosed for varying the cross sectional area of the second apertures relative to the cross sectional area of the venturi tube. The apparatus is adapted to allow the back pressure within the venturi tube (which increases as the fluid flow rate increases) to force an increasing proportion of the flow stream to flow around the venturi tube in order to maintain a relatively constant aspiration rate within the venturi tube. The adjustment mechanisms disclosed include a second plate, similar to the first plate, which is manually rotated and a blocking ring which moves responsive to changes in rate of flow of the fluid flow stream.

This is a divisional of application Ser. No. 08/455,287, filed May 31,1995, issued as U.S. Pat. No. 5,676,173, which is a continuation-in-partof application Ser. No. 08/336,065, filed Nov. 4, 1994, abandoned.

FIELD OF THE INVENTION

The invention relates to a venturi tube apparatus.

BACKGROUND

Venturi tubes are well known in the art for introducing a second fluidinto a first fluid. Typically, the inlet of the venturi tube is attachedto a conduit for the first fluid, and the second fluid is introducedthrough a second inlet, hereafter called an aspirator inlet, so that thecombined fluid exits through the venturi's outlet. In operation, the gasor liquid to be introduced is sucked into the venturi through theaspirator inlet, as the fluid flows through the venturi tube. For agiven venturi tube, the aspiration rate depends on the flow rate of thefluid which passes through the venturi inlet and the viscosity of thefluids.

One of the major problems associated with conventional venturi tubes isthat any single tube can only operate over a narrow range of fluid flowrates. This is in part because back pressure produced within the venturiincreases greatly with increases in the fluid flow rate. It is knownthat this problem can be overcome by connecting an external bypasssystem to the fluid conduit, in parallel to a venturi tube, so that aportion of the fluid flow stream flowing through the conduit bypassesthe venturi by flowing through the bypass system. Conventional bypasssystems have several limitations including being costly, bulky andrequiring complex plumbing which hinders easy installation inassociation with an existing fluid conduit.

There exists a need for a simple venturi tube apparatus which can beadded easily to an existing fluid carrying conduit and which can operateover a wider range of fluid flow conditions.

SUMMARY OF THE INVENTION

The invention provides for the insertion of a venturi tube directlywithin a fluid flow stream. A broad aspect of the invention provides anapparatus for use within a conduit for a fluid flow stream comprising aventuri tube having an inlet, an aspirator inlet and an outlet; andsupporting means for supporting said venturi tube within said conduit insuch a manner that said venturi tube is aligned axially in the directionof said flow stream with the aspirator inlet not in contact with thefluid flow stream.

Another aspect of the invention provides a fluid flow control meanswhich divides the fluid flow stream into a first stream which flowsthrough the venturi tube and a second stream which flows around theventuri tube. The fluid flow control means is adapted to allow the backpressure within the venturi tube (which increases as the fluid flow rateincreases) to force an increasing proportion of the flow stream to flowaround the venturi tube in order to maintain a relatively constantaspiration rate within the venturi tube. This permits a relativelyconstant and consistent operation of the venturi tube over a wider rangeof fluid flow rates by increasing the flow rate of the second streamrather than increasing the flow rate of the first stream as the rate ofthe fluid flow stream increases.

In another aspect, the invention provides means for inducing a vortex inthe second stream, preferably at or near the venturi tube outlet. Thisinduced vortex produces a surprising increase in the venturi effect andreduces backpressure at any given fluid flow rate. In addition, thevortex increases the mixing action of the first and second streams. Theinduced vortex permits more constant flow rates in the first stream,yielding a satisfactory venturi effect over a wider range of fluid flowrates.

Another aspect of the invention provides for reduced pressure at theventuri tube outlet by means of an increased pipe diameter at that pointrelative to the diameter of the fluid flow inlet pipe. Preferably, thisincreased pipe diameter persists over a distance of about 1 to about 4pipe diameters extending from the venturi outlet; even more preferably,over a distance of about 2 to about 3 diameters from that point.

In another aspect the invention is directed to an aspirator inlethaving, at its point of intersection with the venturi tube, a diameterselected so as to achieve a desired flow velocity (or range of flowvelocities) as the second fluid is introduced into the first fluid.Preferably, the inner diameter of the aspirator inlet will be selectedso as to achieve, in conjunction with the other components of theinvention as described herein, high flow velocities, which may besubsonic, sonic or hypersonic, over at least a portion of the operatingrange of fluid flow rates for a given system.

In a preferred embodiment of the invention the in-line venturi comprisesvortex inducing means and increased fluid flow outlet diameter relativeto the fluid flow inlet pipe diameter. In a particularly preferredembodiment, the aspect ratio is adjusted so as to provide for optimalvortex formation under the particular flow conditions of the system, andthe aspirator inlet comprises an aspirator tube.

In a preferred embodiment of the invention the supporting meanscomprises a plate or disc inserted within the conduit (or integraltherewith). The fluid flow control means comprises first passage meansthrough said plate or disc for allowing said first stream to flowthrough said venturi tube and second passage means, preferably in theform of at least one aperture, through said plate or disc, for allowingsaid second stream to flow. The aspiration rate of the venturi tube, fora given fluid flow rate, is determined by the cross sectional area ofthe venturi tube relative to the cross sectional area of the secondpassage means. The cross section of the second passage means cantherefore be preset for a given venturi tube to be used within a fluidflow stream having a given flow rate, in order to achieve a desiredaspiration rate.

Preferably said fluid flow control means further comprises adjustingmeans for adjusting the flow rate of the second stream, typically byadjustably blocking (or unblocking) said second passage means, in orderto maintain a relatively constant flow rate through the venturi tube.Thus the total cross sectional area of the at least one aperture of thesecond passage means, relative to the cross sectional area of theventuri tube, can be adjusted by varying the extent the apertures of thesecond passage means are blocked. This allows for a greater range offlow rates of the fluid flow stream to be used with a given venturi tubeto produce a desired aspiration rate.

In one embodiment, the adjusting means allows for adjustment of theextent to which the second passage means is blocked.

In another embodiment, the adjusting means includes regulating means,responsive to changes in the fluid flow rate for regulating the flowrate of the second stream. In one such embodiment, the regulating meanscomprises a blocking means which is biased towards the plate (or disc)by some resilient means, so as to block the second passage means. Theblocking means is moved away from the second passage means, against thebias of the said resilient means, by the fluid flow stream as the flowrate (and resulting pressure) increases. Furthermore, both suchadjusting means can be utilized together, if desired.

In some applications (for example in cases of high back pressuredownstream from the venturi tube), it is desirable to increase thepressure drop across the venturi tube. This acts to increase theaspiration rate of the venturi tube. Consequently, another aspect of theinvention provides for an optional constriction means for reducing thepressure at the venturi tube outlet, by constricting the flow of thesecond stream, in the vicinity of the venturi tube outlet.

In another embodiment, the invention comprises a venturi support bodyhaving, at the fluid inflow end, a concave face which acts to direct theincoming fluid stream toward a central aperture and therethrough into aventuri tube which is partly integral to the venturi support body andpartly a separate tube held in close apposition against a mating surfaceon the venturi support body, in which the separate venturi tube furthercomprises one or more flow directors which cause the formation of avortex in a portion of the fluid stream which is diverted through aseries of apertures surrounding the central aperture as a function ofincreasing back pressure within the venturi tube, and in which thediameter of the fluid flow outlet pipe is greater than the diameter ofthe fluid flow inlet pipe over a distance of not less than between about2 and about 3 outlet pipe diameters beginning at the venturi tubeoutlet.

These foregoing aspects of the invention, together with other aspectsand advantages thereof, will be more apparent from the followingdescription of the preferred embodiments thereof, taken in conjunctionwith the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, perspective view of a preferred embodiment of thepresent invention, with the conduit shown in partial cutaway.

FIG. 2 is a cross sectional view of the assembled parts illustrated inFIG. 1.

FIG. 3 is a cross sectional view taken along line 3--3 of FIG. 2.

FIG. 4 is an exploded, perspective view of another embodiment of thepresent invention, with the conduit shown in partial cutaway.

FIG. 5 is a cross sectional view of the assembled parts illustrated inFIG. 4, but with the tube 17 omitted for clarity.

FIG. 6 is an exploded, perspective view of a variation of the embodimentshown in FIGS. 4 and 5, showing an alternative regulating means.

FIG. 7 is a cross sectional view of the assembled parts illustrated inFIG. 6, but with the tube 17 omitted for clarity.

FIG. 8 is a front plan view of the alternative regulating means of FIGS.6 and 7.

FIG. 9 is a cross sectional view along line 9--9 of FIG. 8 with thespokes 215 shown in phantom.

FIG. 10 is an exploded, cross sectional view of a preferred embodimentof the invention.

FIG. 11 is a cross sectional view of the assembled parts shown in FIG.10.

FIG. 12 is a perspective view of the embodiment shown in FIGS. 10 and11, with flow directors 605 shown in partial cutaway, omitting adjustingmeans 650 and conduit 500 for clarity.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2 show a preferred embodiment of the present inventioninstalled within a conduit 20 through which a fluid can flow in astream. In this embodiment a venturi support body, shown generally at10, comprises a disc 24 which is sized to closely fit within cylindricalconduit 20. Any suitable means for securing disc 24 in a sealingrelationship within the conduit 20 can be used (for example, a suitableadhesive, a shoulder, or disc 24 and conduit 20 can be molded as oneintegral unit). The securing means should be sufficiently strong towithstand the pressures of the fluid flow stream and to keep the supportbody in sealing relationship with the conduit. In the preferredembodiment shown in FIGS. 1 and 2, an inner seating ring 300, attachedto the inside of conduit 20, prevents downstream movement of disc 24,while allowing withdrawal of the unit, in the upstream direction, formaintenance if necessary. A key 301, attached to the inside of conduit20, fits through keyway 302 in disc 24 to prevent rotation of disc 24.

Face 23 of disc 24, which faces the fluid flow stream, is preferablyconcave. Preferably located centrally within face 23 is aperture 25leading into pipe 26 which extends axially from disc 24 on the sideremote from face 23. Pipe 26 can be integral with disc 24 or connectedthereto. Disc 24 also has apertures 27 which allow the fluid flow streamto pass through disc 24. Disc 24 acts to obstruct the fluid flow streamso that all the flow must be through apertures 25 or 27. In thepreferred embodiment shown, apertures 27 are circular holes through disc24, arranged in a circular pattern around aperture 25. Apertures 27 canvary in size, shape, and orientation.

Preferably an adjusting means is included to adjust the flow rate of thesecond stream (i.e., the portion of the fluid flow stream which flowsaround the venturi tube), by adjustably blocking (or unblocking)apertures 27. This adjustment means can either be adjustable, automatic(i.e., responsive to changes in the fluid flow rate) or a combinationthereof.

In the preferred embodiment shown in FIGS. 1 and 2, adjusting means,generally shown at 12, allows for the external adjustment of the extentto which the apertures 27 are blocked. In this embodiment, adjustingmeans 12 comprises a disc 30 which is able to rotate with respect todisc 24, such as by being journalled on pipe 26. Disc 30 includescentral aperture 35 for receiving pipe 26. Disc 30 also has apertures 31which preferably are similar in size and spacing to apertures 27 of disc24. Disc 30 obstructs the flow of the fluid stream through apertures 27,except for flow through apertures 31, which depends on the extent towhich apertures 31 are in axial alignment with apertures 27. By rotatingdisc 30 with respect to disc 24, the degree of axial alignment ofapertures 31 with respect to apertures 27, and thus the extent apertures27 are blocked, is adjusted. FIGS. 1, 2, and 3 show one form of rotationmeans for rotating disc 30. In this embodiment, disc 30 includes athreaded hole 40 adapted to receive actuator 14. As can be seen in FIG.3, actuator 14 extends outwardly through slot 45 of conduit 20, gasket16b, gasket 16a and washer 16c. Actuator 14 comprises a threaded boltfor engaging threaded hole 40, a handle which acts as a lever, and ashoulder 14b for engaging gasket 16b. Keyway 303 ensures that disc 30 isnot obstructed by key 301 as the disc is rotated or during withdrawal ofthe assembly.

During normal operation, actuator 14 is screwed down in its tightenedposition. Shoulder 14b presses against gaskets 16b and 16a which serveto seal against leaks through washer 16c and slot 45 respectively, andalso frictionally maintains disc 30 in a fixed position. In order torotate disc 30, actuator 14 is externally loosened sufficiently so thatit is free to move with respect to conduit 20, but so that a portion ofit remains within threaded hole 40. Actuator 14 is then moved, as shownby arrows 47 in FIG. 3, in order to rotate disc 30. Actuator 14 is thenretightened in order to prevent further rotation of disc 30 with respectto disc 24. Alternative rotation means can be implemented. For exampledisc 30 can be provided with a one part of a worm gear or bevel geararrangement (not shown), with the mating gear arrangement on a member(not shown) which extends through the conduit 20. Thus, by rotating themember from outside the conduit, the gear arrangement will rotate thedisc 30.

A locking nut 13, screwed onto pipe 26 against a shoulder, maintainsdisc 30 in close proximity to disc 24, but with a sufficient gap so asto allow disc 30 to rotate. Pipe 26 is connected, for example by meansof a threaded connection and optional locking nut 304, to the inlet ofthe venturi tube 11. In this embodiment, the venturi tube is supportedwithin the conduit by pipe 26, which is in turn supported by disc 24,and aperture 25 acts as an inlet passage through disc 24 leading to pipe26, and hence to the venturi tube inlet. Locking nut 304 preventsrotation of the venturi tube with respect to the pipe 26. Alternativesupporting means can be provided while remaining within the scope of theinvention. For example, the venturi tube 11 can be directly received andseated in aperture 25 of disc 24, with disc 30 journalled on venturitube 11. Alternatively, pipe 26 can be flexible, and the venturi tubecan be supported by spacer arms or struts which extend from it to theconduit wall.

Tube 17 leading to aspirator inlet 18 of venturi tube 11, is used forintroducing a gas or liquid into the venturi tube. Tube 17 leads to anexternal source (not shown) of the gas or liquid to be introduced or canadditionally include a pressure gauge (not shown), if desired. Dependingon the application, tube 17 can either extend directly through a borehole in the conduit 20 (not shown), or penetrate through the wall of theconduit 20 through a conventional compression fitting (not shown) at aconvenient point along the conduit 20.

In operation the fluid flow stream within conduit 20 is diverted intoinlet passage 25 and apertures 27 of disc 24 by face 23. Preferably face23 is concave in order to help funnel a portion of the fluid flow stream(i.e., the first stream) through inlet passage 25 and consequently intoventuri tube 11, by means of pipe 26. For any given flow rate of thefluid flow stream, the flow rate of the first stream, and the flow rateof the second stream (i.e., the portion which flows through apertures27) depends on the relative cross sectional area of the apertures 27compared with the cross sectional area of the venturi tube 11, and theback pressure produced within venturi tube 11. As the fluid flow rateincreases, the resulting back pressure within venturi tube 11 increases,thereby forcing a larger proportion of the flow stream to flow throughapertures 27 (i.e., increases the flow rate of the second stream),rather than increasing the flow rate through venturi tube 11. Thus,although any given venturi tube can only operate effectively for anarrow range of flow rates, the invention allows for operation of theventuri tube over a greater range of fluid flow stream flow rates thanwould be possible with the venturi tube alone, by keeping the flow rateof the first stream relatively constant over the greater range.

If the flow rate of the fluid flow stream is approximately constant, thesize of apertures 27 can be predetermined to produce a desired flow ratethrough the venturi tube 11.

However if the flow rate of the fluid flow stream is variable, thenoptional adjusting means 12 is preferably added for adjusting theeffective cross sectional area of the apertures 27 (in relation to thecross sectional area of the venturi tube 11). In the preferredembodiment shown in FIGS. 1 and 2, this adjustment is made by rotatingdisc 30, changing the axial alignment of apertures 31 and 27, therebyadjusting the degree to which apertures 27 are blocked by disc 30, ashereinbefore discussed. These adjustments change the relative crosssectional area of the apertures 27 in relation to the cross sectionalarea of the venturi tube. This accordingly will change the relativeproportions of the first and second streams for any constant flow rateof the fluid flow stream. Thus for any constant flow rate, for a givenset of fluids, the flow rate of the first stream, and hence theaspiration rate, can be set by appropriately rotating disc 30.Furthermore, this aspiration rate can be monitored by means of a gauge(not shown) located on tube 17, without visual access to the interior ofthe conduit and without opening the venturi tube assembly within theconduit.

In some applications (for example in cases of high back pressuredownstream from the venturi tube), it is desirable to increase the rateof flow through the venturi tube. Consequently, another aspect of theinvention provides for an optional means for reducing the pressure atthe venturi tube outlet, by constricting the flow of the second stream,in the vicinity of the venturi tube outlet. This operates to increasethe drop in pressure across the venturi tube, thus increasing itsaspiration rate. A preferred means for reducing the pressure at theventuri tube outlet is shown in FIGS. 1 and 2 as the optional flowdiverter 15 affixed to the outlet of the venturi tube. Flow diverter 15narrows the effective size of the conduit 20 in the vicinity of theventuri tube outlet. The second stream is therefore forced through thegap between the diverter 15 and the conduit 20. This increases the flowrate of the second stream as the second stream flows through the gapbetween diverter 15 and conduit 20, thus increasing the suction at theoutlet end of the venturi tube. Flow diverter 15 is preferably conicallyshaped, in order to reduce resistance to the fluid flow. Other means forreducing the effective size of the conduit in the vicinity of theventuri tube outlet can be employed. For example, a ring extendingradially inward from the inside perimeter of the conduit (not shown) canbe utilized.

An alternative adjusting mechanism, not shown, for the rotating disc 30is a blocking mechanism, for blocking apertures 27, which moves axiallytowards or away from the disc 24. In this embodiment, rather thanrotating the adjusting mechanism, the effective size of the apertures 27(in relation to the diameter of the venturi tube 11) is adjusted byaxially moving a series of blockers (one for each aperture 27) awayfrom, or closer to, the apertures 27. Each blocker can, for example beconically shaped and sized to totally occlude each aperture 27 if fullyinserted within aperture 27, and partially occlude aperture 27 ifpartially withdrawn. Each blocker can conveniently be attached to acentral hub by a spoke, for example, as illustrated in FIGS. 8 and 9.The hub can then be axially moved in order to vary the gap between theblockers and the apertures and thus the effective size of the secondpassage means through which the second stream can flow.

FIGS. 4 and 5 illustrate another embodiment of the invention, wherein anautomatic adjustment means for regulating the flow rate of the secondstream, responsive to changes in the fluid flow rate, has been added tothe embodiment shown in FIGS. 1 and 2. In the embodiment shown in FIGS.4 and 5, this regulating means, generally shown at 100, is illustratedfor use in conjunction with the manually rotatable disk 30 of FIGS. 1and 2. It should be noted that the regulating means 100 can also be usedwithout disk 30. FIGS. 4 and 5 show essentially the same apparatus asshown in FIGS. 1 and 2, with the corresponding parts labelled with thesame numbers as that of FIGS. 1 and 2, except for a change to the threadand shoulder arrangement on pipe 26; the addition of automaticadjustment means 100; and the removal of locking nut 13.

Blocking ring 60 is mounted on pipe 26 for axial movement towards andaway from disc 30. A helical spring 70 and a locking nut 80 are mountedon pipe 26, with locking nut 80 adjacent pipe shoulder 50. A secondlocking nut 304, adjacent locking nut 80, prevents the venturi 11 fromrotating. Spring 70, which is held in place by locking nut 80, biasesblocking ring 60 against disc 30 such that ring 60 blocks apertures 31.The pressure of the fluid flow stream within the conduit 20 exerts aforce on blocking ring 60 against the bias of spring 70. As the pressureincreases, so does the force. Thus, under low flow stream rates, spring70 biases blocking ring 60 against disc 30, blocking apertures 31, thusforcing the majority of the flow stream (or all the flow stream ifblocking ring 60 totally occludes apertures 31) into the venturi tube.As the flow rate of the flow stream increases the resulting pressureincrease acting on blocking ring 60 moves blocking ring 60 away fromapertures 31, against the bias of spring 70, allowing fluid to flowthrough apertures 31. Thus, as the pressure increases, the proportion ofthe fluid flow stream flowing through the apertures 31 increases untilblocking ring 60 has moved sufficiently away from ring 30 so as to offerno significant resistance to the flow.

In this embodiment, the disc 30 is rotated in order to adjust theinitial effective sizes of the apertures through which the second streamcan flow. The blocking ring 60 will then regulate the actual flowthrough the apertures, allowing increased flow through the apertures asthe flow rate (and resulting fluid pressure) increases, and allowingdecreased flow through the apertures as the flow rate of the fluid flowstream decreases. Thus as the flow rate increases, the portion of thefluid flow stream flowing through the venturi tube will remain constant,but the second stream will increase. If disc 30 is not utilized, theblocking ring 60 is biased towards disc 24, in order to regulate theflow through apertures 27. Furthermore, alternative resilient means canbe substituted for spring 70.

An alternative regulating means is shown generally at 200 in FIGS. 6, 7,8 and 9, replacing the blocking ring 60 of FIGS. 4 and 5. Thisalternative regulating means 200 comprises a series of blockers 220sized and shaped to block apertures 31, or alternatively apertures 27,if disc 30 is not utilized. These blockers are supported by spokes 215which extend radially outward from a hub 210. Blockers 220 areresiliently biased against apertures 31 by a resilient means, such ashelical spring 70, as shown in FIGS. 6 and 7.

In this embodiment, a means is necessary to maintain alignment ofblockers 220 with apertures 31 if disc 30 is rotated. As seen in FIGS. 6and 7, disc 30 is provided with an axially extending sleeve 330 whichsurrounds pipe 26. As shown in FIG. 8, key 205 extends radially inwardfrom hub 210 for sliding axial movement within keyway 206 (as shown inFIG. 7) of sleeve 330. Thus, hub 210 can move axially along sleeve 330,but key 205 within keyway 206 prevents rotation of hub 210 with respectto disc 30. In operation, regulating means 200 works in the same manneras blocking ring 60 in FIGS. 4 and 5, but provides easier flow for thesecond stream once the pressure of the fluid flow stream has moved theregulating means 200 away from the disc 30. Alternatively, hub 210 canbe fixed in place, with spokes 215 longer than shown and constructedfrom a sufficiently resilient material so as to act as a living hinge,with the resiliency of spokes 215 biasing the blockers 220 to blockapertures 31.

FIGS. 10, 11 and 12 show another preferred embodiment of the presentinvention. In this embodiment a venturi support body, shown generally at400, comprises a fluid flow inlet 405 having a diameter approximatelyequal to the diameter of the fluid supply inflow pipe (not shown),venturi support body 400 being removably sealably connected to the fluidsupply inflow pipe by means of a standard compression fitting usingthreads 410. Any suitable means for securing venturi support body 400 ina sealing relationship with the fluid supply inflow pipe can be used.For example, the base 415 of venturi support body 400 may have aconcentric groove sized so as to receive an O-ring which seals against asuitable face of the fluid supply inflow pipe (not shown).

In the preferred embodiment shown in FIGS. 10 and 11, venturi supportbody 400 comprises a face 420 which faces the fluid flow stream and ispreferably concave. Preferably located centrally within face 420 isaperture 425, having a diameter approximately 0.100" less than the inletdiameter of integral venturi 430 to which it leads, resulting inshoulder 433. As shown in FIGS. 10 and 11, beginning at shoulder 433,integral venturi 430 is cylindrical at the point of entry of aspiratorinlet 440 and for a short distance beyond aspirator inlet 440, afterwhich it is frustoconical. Face 420 also has apertures 435 which allowthe fluid flow stream to pass through venturi support body 400. Face 420acts to obstruct the fluid flow stream so that all the flow must bethrough apertures 425 or 435. In the preferred embodiment shown,apertures 435 are circular holes through venturi support body 400,arranged in a circular pattern around aperture 425. Apertures 435 canvary in size, shape and orientation. In the preferred embodiment shown,aspirator inlet 440 is sized to receive aspirator tube 445 by means of athreaded connection.

Venturi support body 400 is sealably removably connected to conduit 500.In the preferred embodiment shown, the sealable, reversible connectionmeans comprise matching left-hand thread 450 on venturi support body 400and conduit 500, and shoulder 455 in venturi support body 400 which cansupport an O-ring (not shown) against which the end of conduit 500sealably bears as it is drawn toward shoulder 455. Any suitable sealingmeans may be employed; for example, shoulder 455 itself can act as thesealing surface against which the inlet end 505 of conduit 500 may bearwhen conduit 500 is threaded onto venturi support body 400. Threads 530allow conduit 500 to be sealably, removably connected to the fluidsupply outflow pipe (not shown) by means of a standard compressionfitting. Any suitable means for securing conduit 500 in a sealingrelationship with the fluid supply outflow pipe can be used. For thispurpose, for example, outlet end 540 of conduit 500 is preferably sizedto match the diameter of the fluid supply outflow pipe and includes aconcentric groove sized to receive an O-ring (not shown) which sealsagainst a suitable surface of the fluid supply outflow pipe (not shown).Fluid flow outlet 520 of conduit 500 has a diameter which, in thepreferred embodiment shown, is greater than the diameter of fluid flowinlet 405 of venturi support body 400.

Shoulder 510 of conduit 500 bears against venturi tube 600, which, inturn, fits in closely mating surfaces of venturi support body 400. Inthe preferred embodiment shown, venturi tube 600 comprises flowdirectors 605 which are angled with respect to the direction of thesecond stream (i.e., the portion of the fluid flow stream which flowsthrough apertures 435). Adjusting means 650 comprises disk 655 andhelical spring 660.

The preferred embodiment of FIG. 10 is shown assembled in FIG. 11.Venturi support body 400 and conduit 500 are shown sealably drawntogether by means of left-hand threads 450. Shoulder 510 forces venturitube 600 into venturi support body 400 such that venturi tube 600 formsan extension of integral venturi 430. It is not necessary that venturitube 600 mate precisely with venturi support body 400 as shown in FIG.11; for example, where an O-ring is interposed between shoulder 455 ofventuri support body 400 and inlet end 505 of conduit 500 to effect aseal (not shown), a gap between the mating surfaces of venturi supportbody 400 and venturi tube 600 will exist which is equal in size to thecompressed O-ring diameter, and such a gap will not impede the desiredventuri effect. Helical spring 660 biases disk 655 against apertures 435of venturi support body 400, and simultaneously biases venturi tube 600against shoulder 510 of conduit 500.

In operation, the fluid flow stream from the fluid supply inflow pipeenters fluid flow inlet 405 and is diverted into apertures 425 and 435by face 420. The preferred concavity of face 420 assists in funneling aportion of the fluid flow stream (i.e., the first stream) throughaperture 425 and into the venturi formed by integral venturi 430 andventuri tube 600. At a given fluid flow stream flow rate, the firststream flow rate and the second stream flow rate (i.e., the rate of theflow of that portion of the fluid flow stream which flows throughapertures 435) is a function of the ratio between the cumulativecross-sectional area of apertures 435 and the cross-sectional area ofaperture 425, and of back pressure produced within the venturi tube.These values typically will be selected in order to achieve a desired(preferably, a relatively constant) amount of venturi draw or suctionover the anticipated operational range of fluid flow stream flow ratesfor the system.

In practice, the cross sectional area of aperture 425 typically will beselected in order to achieve the desired venturi draw at the low end ofthe operational range. At low fluid flow stream flow rates, disk 655 isbiased against apertures 435 by helical spring 660, with the result thatapertures 435 are occluded and substantially all of the fluid flowpasses through aperture 425. As the fluid flow rate increases, theincrease in back pressure within the venturi tube forces an increasingproportion of the fluid flow stream through apertures 435, which areprogressively opened as the force of the second stream flow overcomesthe bias of disk 655 against apertures 435 from helical spring 660.Adjusting means 650, then, acts to maintain a relatively constant fluidflow rate of the first stream over a range of second stream flow rates.Thus, where the range of the fluid flow rates is known for a givensystem, the characteristics of helical spring 660 may be selected suchthat adjusting means 650 produces an acceptable flow rate of the firststream through the venturi tube over that range.

In the embodiment shown, the ratio of the cross sectional area ofaperture 425 to the cumulative cross sectional area of apertures 435 isapproximately 1:2, and typically will be selected such that the firststream flow rate and the second stream flow rate are approximately equalover the operational range.

As described above, it is frequently desirable to increase the rate offlow through the venturi tube. In the preferred embodiment shown inFIGS. 10-12, the pressure at the venturi tube outlet is decreased due tothe fact that the diameter of the fluid flow outlet 520 is greater thanthe diameter of the fluid flow inlet 405. While any increase in fluidflow outlet 520 diameter over fluid flow inlet 405 diameter will produceincreased flow rate through the venturi tube, it is preferred that theincrease in pipe diameter be between about 25% and about 75%; morepreferably, between about 35% and about 65%; and even more preferably,about 50%. The length of the increased pipe diameter, measured from theoutlet of venturi tube 600 (which, in the embodiment shown, correspondsto the location of shoulder 510), should be a minimum of between about 1and about 4 pipe diameters; preferably between about 2 and about 3 pipediameters. Longer lengths will, of course, also work.

As shown in FIG. 12, venturi tube 600 comprises flow directors 605 whichare oriented at an angle to the direction of the second stream as itemerges from apertures 435 and passes disk 655. As the second streampasses through flow directors 605, a vortex is created in the fluid flowoutlet 520 portion of conduit 500. The angle at which flow directors 605intersect the direction of the second stream may be varied over a widerange, for example, between about 5° and about 95°; preferably betweenabout 10° and about 90°; more preferably between about 15° and 85°; evenmore preferably between about 20° and about 80°; more preferably still,between about 25° and about 75°; yet more preferably, between about 30°and about 70°, or between about 35° and about 65°, or between about 40°and about 60°; most preferably between about 45° and about 55°, in orderto achieve a satisfactory vortex. In the embodiment shown, the angle offlow directors 605 is about 45°. In practice, the vortex formed in thesecond stream by flow directors 605 can extend for a considerabledistance into the fluid supply outflow pipe (not shown) beyond outletend 540.

This induced vortex produces a surprising increase in the venturi effectand reduces backpressure at any given fluid flow rate, and contributesto the unexpected and surprisingly wide operational range of theembodiment shown. The vortex also contributes to improved mixing of thefirst stream with the second stream as the first stream emerges from theoutlet of venturi tube 600. Formation of an optimal vortex is dependentupon a number of factors, including the angle and cross sectional areaof the flow directors and the increase in diameter of fluid flow outlet520 over the diameter of fluid flow inlet 405.

In the embodiment shown in FIG. 12, flow directors 605 are a series ofradial fins formed at an angle of about 45% to the direction of thesecond fluid stream as it emerges from apertures 435, and arranged in acircular pattern around the outlet of venturi tube 600. The size andshape of flow directors 605 may be varied. The cumulative crosssectional area of flow directors 605 may be smaller than, larger than,or equal to that of apertures 435. The choice of flow director size andshape, but particularly size, will affect the characteristics of thevortex induced in the second fluid stream as it emerges from apertures435. Preferably, the cumulative cross sectional area of flow directors605 will be no larger than that of apertures 435; even more preferably,the cumulative cross sectional area of flow directors 605 will be equalto or, most preferably, slightly less than that of apertures 435. Flowdirectors 605 may comprise circular angled holes. Alternatively, flowdirectors 605 may take the form of the radial fin shown in cutaway inFIG. 12 which extend all the way to the inner wall of conduit 500 andrest directly on shoulder 510, such that the outer wall of flowdirectors 605 is effectively formed by the inner wall of conduit 500 asopposed to being an integral part of venturi tube 600 as shown in FIG.12.

In another aspect the invention is directed to an aspirator inlethaving, at its point of intersection with the venturi tube, a diameterselected so as to achieve high flow velocities as the second fluid isintroduced into the first fluid. Preferably, the inner diameter of theaspirator inlet will be selected so as to achieve subsonic, sonic orhypersonic flow velocities over at least a portion of the operatingrange of fluid flow rates for a given system.

Selection of the inner diameter of the aspirator inlet is varieddepending upon the fluid flow rates for which a given system isdesigned, so as to achieve a desired second fluid introduction flowvelocity over the operating range. The flow velocity at which the secondfluid is introduced into the first fluid will affect the degree to whichthe second fluid (either the first or the second liquid may comprise agas or a liquid) is incorporated into the first fluid, and can bevaried, then, to achieve a desired degree of incorporation.

For example, where the first fluid is a liquid such as water and thesecond fluid is a gas such as ozone, selection of the aspirator inletinner diameter, as well as other variables of the design of theapparatus as described herein, may be determined in order to maximizethe incorporation of ozone into the water, thereby minimizingunincorporated ozone offgas. Similarly, where it is desired to introducea solute into the first fluid, the choice of flow velocity, and thus ofthe inner diameter of the aspirator inlet, will vary depending upon thenature and properties of the solute. Thus, less soluble solutes mayrequire higher flow velocities to be incorporated into a first fluid ata desired concentration.

In the preferred embodiment shown in FIGS. 10-12, venturi support body400 comprises integral aspirator inlet 440. Because aspirator inlet 440is an integral part of venturi support body 400, it does not come intocontact with the second fluid stream. In the embodiment shown, aspiratorinlet 440 is formed such that shoulder 433 is uninterrupted; it is alsopreferred to form aspirator inlet 440 completely through venturi supportbody 400, such that shoulder 433 is interrupted (not shown). Aspiratorinlet 440 is sized to receive aspirator tube 445 by means of a threadedconnection. Aspirator tube 445, which is replaceable, is fabricated froma material having sufficient tensile strength to withstand the forcesexerted in operation upon aspirator tip 448 where it enters integralventuri 430; a preferred material having suitable characteristics forthis purpose is stainless steel. It is preferred that aspirator tip 448have a slight conical depression formed therein as shown, and that it beslightly below the surface of integral venturi 430 in operation. Wherethe second fluid is ozone gas, aspirator tube 445 is preferablyconstructed of 316 stainless steel. It will be appreciated thataspirator tube 445 of the embodiment shown may easily and economicallybe replaced if it should become worn, or in order to optimize theapparatus for a particular first fluid, second fluid or both.

The inner diameter of aspirator tube 445 may be varied as describedherein. In the embodiment shown, the inner diameter of aspirator tube445 is about 0.25" at the inlet end, and is reduced to about 0.046" ataspirator tip 448. The embodiment shown was designed to consistentlydraw between about 15 ft³ /hr and about 17 ft³ /hr at first fluid flowrates of 40 gal/min or greater. It has been shown to draw within thesespecifications at first fluid flow rates as great as 120 gal/min, givingit a surprisingly wide operational range of at least 80 gal/min. Basedupon the results of testing performed so far, it is expected that thisembodiment will continue to draw within specifications at first fluidflow rates in excess of 120 gal/min. Moreover, the embodiment shown hasbeen demonstrated to draw near specifications at first fluid flow ratesas low as 35 gal/min, and to continue to draw at first fluid flow ratesas low as 18-20 gal/min. The embodiment shown has a fluid flow inlet 405diameter of about 2.0", a fluid flow outlet 510 diameter of about 2.5",and an aperture 425 diameter of about 0.625".

The preferred embodiment shown in FIGS. 10-12 is particularly wellsuited for introducing a second fluid comprising ozone gas into a firstfluid comprising water. Unexpected and surprisingly high incorporationof ozone into water has been observed in the operation of thisembodiment. Further, while not wishing to be bound to a particulartheory, it is believed that the flow velocities achieved at aspiratortip 448 in the operation of this embodiment effect a chemical change inthe ozone as it is incorporated into the water, which may include theconversion of ozone to hydroxyl radicals. This embodiment isparticularly useful for the purification of water by ozone.

The above embodiments can be used for fluids that can be used with aconventional venturi. As is known in the art, the fluids must besufficiently viscous so as to be aspirated. For example, the inventioncan be used as an ozonator for introducing ozone into water. Preferably,the various parts of the above mentioned embodiments are formed byinjection molding of a suitable thermoplastic which is chemically inertwith respect to the fluids used. The above described embodiments aredesigned for installation within existing conduits. For facilitatingsuch installation, the apparatus can be pre-installed in a section ofconduit, with the said section of conduit subsequently inserted withinan existing conduit.

It will be apparent that many other changes may be made to theillustrative embodiments, while falling within the scope of theinvention and it is intended that all such changes be covered by theclaims appended hereto.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. Apparatus for use withina conduit for a fluid flow stream comprisinga venturi tube having aninlet, an aspirator inlet and an outlet; supporting means for supportingsaid venturi tube within said conduit in such a manner that said venturitube is aligned axially in the direction of said fluid flow stream;fluid flow control means, comprising first passage means for allowing afirst stream to flow and second passage means for allowing a secondstream to flow for dividing said fluid flow stream into a first streamwhich flows through said venturi tube and a second stream which flowsaxially around said venturi tube, wherein the aspirator inlet is not incontact with the second stream; and vortex inducing means in said secondpassage means for inducing net axially symmetric vorticity in said fluidflow stream.
 2. Apparatus as claimed in claim 1 wherein said net axiallysymmetric vorticity is induced at or near said outlet.
 3. Apparatus asclaimed in claim 2 wherein said supporting means comprises a platepositioned within said conduit in a sealable relationship therewith,said fluid flow control means including:first passage means through saidplate for allowing said first stream to flow; and second passage meansthrough said plate for allowing said second stream to flow.
 4. Apparatusas claimed in claim 3 further comprising adjusting means for adjustingthe flow rate of the second stream.
 5. Apparatus as claimed in claim 4further comprising constriction means for reducing the pressure at theventuri tube outlet by constricting the flow of the second stream in thevicinity of said venturi tube outlet.
 6. Apparatus as claimed in claim 4wherein said second passage means comprises at least one aperturethrough said plate and said adjusting means comprises means for varyingthe cross sectional area of said at least one aperture by adjustablyblocking said at least one aperture.
 7. Apparatus as claimed in claim 5wherein said second passage means comprises at least one aperturethrough said plate and said adjusting means comprises means for varyingthe cross sectional area of said at least one aperture by adjustablyblocking said at least one aperture.
 8. Apparatus as claimed in claim 4wherein said adjusting means comprises regulating means, responsive tochanges in the fluid flow rate, for regulating the flow through saidsecond passage means, allowing the flow through said second passagemeans to increase as the flow rate of the fluid flow stream increasesand decrease as the flow rate of the fluid flow stream decreases. 9.Apparatus as claimed in claim 8 wherein said regulating means comprises:blocking means for blocking said second passage means;resilient meansfor biasing said blocking means towards said second passage means.